Fortune quoted Andy Campion, Nike’s chief financial officer: “What’s fascinating about [Parker’s] use of questions is that it leaves other leaders empowered to find the answers themselves and act on them.”

That observation closely mirrors those that other Nike employees have made in the past.

A 2009 USA Today article noted that employees in Nike’s research lab “say there’s no telling when Parker will drop in and start reeling off questions.”

Parker acknowledges that inquisitiveness is a key part of his leadership strategy and a way to support his employees’ development. In 2012, he told Fast Company, “I end up asking a lot of questions, so the team thinks things through. I don’t say ‘Do this, do that.’ I’m not a micromanager. I don’t believe in that. … At Nike, we have incredibly strong people. They know what to do.”

Research suggests that Parker’s hit on a winning management tactic: Leaders who ask questions and encourage their team to find the answers tend to be more effective than those who try to know and do it all themselves.

Writing in The Harvard Business Review, Liz Wiseman and Greg McKeown identify two types of leaders: “diminishers” and “multipliers.” Diminishers tend to minimize intelligence among their team because they assume their employees’ abilities are fixed; multipliers believe abilities can be cultivated. Wiseman and McKeown found that multipliers tend to lead teams that are up to twice as productive as those led by diminishers.

One key characteristic of multipliers is asking hard questions and prompting people to go find the answers. Coming up with solutions boosts employees’ self-efficacy and confidence that they can help solve organizational problems.

“Stop worrying about having all the answers,” Wiseman and McKeown write. “Use your knowledge of the business to ask insightful questions that prompt the members of your team to stop, think, and then rethink.”

For Parker, relentlessly questioning his employees is a way to ensure that people never get too comfortable with one way of thinking. Moreover, it would seem as though he wants employees to start questioning themselves and their own work.

As he told USA Today, “The hardest thing for a company to do is to change when it doesn’t seem like change is necessary.”

Author: Shana LebowitzShana is a strategy reporter for Business Insider. Before joining Business Insider in April 2015, she covered mental health for Greatist and personal finance for LearnVest. Shana studied English and psychology at Brandeis University and received her master’s degree in English literature from Columbia University.